So I gig my 800 about 6 times a month and never have any problems until I play the church every single time something goes wrong but one thing it always does is blow the 500 ma fuse and i'm plugged into a furman m8x so surges should not be the cause so every time I take it to my tech and have a full run through everything checks out and its good until the church and keep in mind i'm playing probably at around 2 when at the other gigs I have it dimed.

I'm not an amp tech - but now it is starting to sound like a more serious issue. You said you have an amp tech. Can you have them check your power transformer, filter caps, heater wiring, etc.

I had him test those when he changed the tubes about a month and a half ago he said everything was fine and it was probably just from the power problems because the fuse fixes everything. O I forgot that time the problem was because my power cable had shorted so I bought another one